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A035532
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a(n) = 2*phi(n) if n composite, or 2*phi(n) - (A000120(n)-1) if n prime;.
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0
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1, 2, 3, 4, 7, 4, 10, 8, 12, 8, 18, 8, 22, 12, 16, 16, 31, 12, 34, 16, 24, 20, 41, 16, 40, 24, 36, 24, 53, 16, 56, 32, 40, 32, 48, 24, 70, 36, 48, 32, 78, 24, 81, 40, 48, 44, 88, 32, 84, 40, 64, 48, 101, 36, 80, 48, 72, 56, 112, 32, 116, 60, 72, 64, 96, 40, 130, 64, 88, 48, 137
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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FORMULA
| G.f.: Sum A005187(n) x^n = Sum a(n)*x^n/(1-x^n).
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MATHEMATICA
| Insert[Table[If[PrimeQ[n], 2*EulerPhi[n] - DigitCount[n, 2][[1]] + 1, 2*EulerPhi[n]], {n, 2, 100}], 1, 1] - Stefan Steinerberger (stefan.steinerberger(AT)gmail.com), Apr 11 2006
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CROSSREFS
| Sequence in context: A139072 A021430 A138676 * A176535 A123498 A123502
Adjacent sequences: A035529 A035530 A035531 * A035533 A035534 A035535
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KEYWORD
| nonn,easy,nice
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AUTHOR
| Daniele Parisse (daniele.parisse(AT)m.dasa.de)
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EXTENSIONS
| More terms from James A. Sellers (sellersj(AT)math.psu.edu)
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